Knowing the direction of a force is important because it helps someone know the motion of the object. if you use a free body diagram, then it becomes easy to see all the forces being applied to an object. if there is more force going one way, the object is accelerating in that direction. if all the forces cancel each other out, then the object is at a constant speed or is at rest.
Yeah i think with a car or a plane:)
Density = 3/5 = 0.6g/cm^3. Since the density is less than the density of water, which is 1, the object will float.
